Field notes: Where did all the acorns go?

Saturday, December 31, 2011

For several years, oaks in the Northeast were prolific acorn producers. The 2010 crop was record-breaking—many willrecall getting hit with acorn rain or slipping on acorns underfoot. This fall, however, acorns were scarce.

While this sounds like good news for the accident-prone, it has ramifications for wildlife and human health. Squirrelsaren't the only animals that depend on acorns for their winter larders. Thecalorie-rich nuts are a staple for an array of forest animals, from chipmunks and mice to deer and black bears.

With acorns at the lowest level seen in 20 years, we can expect more collisions with deer as they leave the forest in search of food. Bears will be more apt to raid our garbage cans. And, as Cary Institute's Richard Ostfeld recently discussed in the New York Times, spring of 2012 will be one of the worst years for Lyme disease in the Northeast.

That's because, this winter, in the absence of acorns, mouse populations will crash. Ostfeld predicts declines could be as steep as 90%. And come May, the tiny nymphal ticks that normally feed on rodents will search for new hosts, increasing our risk of being bitten and infected with Lyme.

Ground-nesting birds will also take a toll as forest predators like hawks and weasels search for alternatives to once-abundant mouse prey.

When it comes to acorns, it has always been feast or famine. But paying attention to cycles in acorn production can provide us with valuable information about the world we live in.